Kim Yo-jong, who is subject to US unilateral sanctions, will visit South for Olympic's opening ceremony, Seoul says.

North Korean leader Kim Jong-un's sister will visit South Korea for the Pyeongchang Winter Olympics, according to Seoul's unification ministry.

Kim Yo-jong will arrive on Friday to attend the opening ceremony as part of the 22-member delegation headed by North Korea's nominal head of state Kim Yong-nam, the ministry said in a statement published on its website on Wednesday.

The Korea Herald newspaper said the move would likely put South Korea in "a tricky position" as Kim, vice director of the propaganda and agitation department of the Workers' Party of Korea, was subject to the US' unilateral sanctions imposed on North Korea.

Another member of her delegation, Choe Hwi, chairman of the national sports guidance committee, is on the UN sanctions list that includes a travel ban, the Korea Herald said.

The newspaper said there were speculations that the delegation would travel to Seoul by Air Koryo, North Korea's state-owned carrier, which would be in violation of the US sanctions imposed in December for its links to weapons proliferation and foreign currency earnings for the regime.

Seoul's foreign ministry has said it will not stoke any controversy with regards to sanctions, saying it is closely coordinated with the US and the international community on the matter, the Herald reported.